On Thu, Jul 04, 2019 at 06:32:56PM +0200, Ladislav Michl wrote: > On Wed, Jul 03, 2019 at 06:33:55PM +0200, Ladislav Michl wrote: > > Following patchset makes console work (patch 1) for at AT91SAM9G20 board > > connected to xhci_hcd and does some cleanup. > > Tested with "console=ttyS0,115200n8 console=ttyGS0,115200n8" on kernel > > command line and following inittab: > > console::respawn:/sbin/getty -L 115200 ttyS0 vt100 > > console::respawn:/sbin/getty -L 115200 ttyGS0 vt100 > > > > There are issues remaining: > > > > - first usb disconnect works while each next triggers WARN_ON in gs_close: > > ------------[ cut here ]------------ > > WARNING: CPU: 0 PID: 501 at drivers/usb/gadget/function/u_serial.c:706 gs_close+0x3c/0x1e4 > > Modules linked in: > > CPU: 0 PID: 501 Comm: getty Not tainted 5.2.0-rc7 #44 > > Hardware name: Atmel AT91SAM9 > > [<c0107514>] (unwind_backtrace) from [<c01051c0>] (show_stack+0x10/0x18) > > [<c01051c0>] (show_stack) from [<c05465a8>] (dump_stack+0x18/0x24) > > [<c05465a8>] (dump_stack) from [<c010fa80>] (__warn+0xcc/0xe4) > > [<c010fa80>] (__warn) from [<c010fad0>] (warn_slowpath_null+0x38/0x48) > > [<c010fad0>] (warn_slowpath_null) from [<c03b6648>] (gs_close+0x3c/0x1e4) > > [<c03b6648>] (gs_close) from [<c03036b0>] (tty_release+0x1d4/0x460) > > [<c03036b0>] (tty_release) from [<c01ce464>] (__fput+0xe4/0x1b0) > > [<c01ce464>] (__fput) from [<c0124e1c>] (task_work_run+0x8c/0xa8) > > [<c0124e1c>] (task_work_run) from [<c011155c>] (do_exit+0x354/0x814) > > [<c011155c>] (do_exit) from [<c0111a9c>] (do_group_exit+0x54/0xb8) > > [<c0111a9c>] (do_group_exit) from [<c011a190>] (get_signal+0x18c/0x658) > > [<c011a190>] (get_signal) from [<c0104bbc>] (do_work_pending+0xe0/0x44c) > > [<c0104bbc>] (do_work_pending) from [<c0101068>] (slow_work_pending+0xc/0x20) > > Exception stack(0xc3797fb0 to 0xc3797ff8) > > 7fa0: 00000000 beb87d0c 00000001 00000000 > > 7fc0: 0009a150 00000000 00099c04 00000003 0009a198 0007e049 00099bd4 0009a1e4 > > 7fe0: b6e3f000 beb87cd8 00018210 b6dbcc40 60000010 00000000 > > ---[ end trace 70af570fde0de49b ]--- > > This one is explained in drivers/tty/serial/ip22zilog.c line 751 (see also > __tty_hangup) And it also explains why patch 2 in this serie is actually wrong. > Will send v2. As an naive approach I tried following: diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 130613751723..4551005a9d23 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -701,6 +704,9 @@ static void gs_close(struct tty_struct *tty, struct file *file) spin_lock_irq(&port->port_lock); + if (test_bit(TTY_HUPPING, &tty->flags)) + goto exit; + if (port->port.count != 1) { if (port->port.count == 0) WARN_ON(1); However this way port->port.count never drops back to zero. Any ideas?